1. Technical Field of the Invention
The present invention relates to a contact portion structure of a female connector terminal, and more specifically to a contact structure between a pair of flat plate-shaped contact portions of a female terminal and a contact pin of a male terminal.
2. Description of the Related Art
In general, a male terminal is formed with a hollow contact pin portion and a wire clamping portion. On the other hand, a female terminal is formed with a cylindrical portion electrically connected to the hollow contact pin portion of the male terminal and a wire clamping portion. The contact pin of the male terminal and the cylindrical portion of the female terminal are usually formed by rounding a thin metal plate from both the sides thereof so as to be joined at the central junction portion thereof, respectively. In this case, however, when the thin metal plate is bent into a cylindrical shape, since the outer diameter of the male terminal contact pin and the inner diameter of the female terminal cylindrical portion tend to disperse in dimension, there exists a problem in that the management of dimensions of these terminal parts is troublesome.
To overcome this problem, Japanese Published Unexamined Utility Model Application No. 3-118572 discloses such a female terminal that an end of the female terminal is formed by flat plate-shaped contact portions. In more detail, a cylindrical elastic portion of the female terminal is formed by rounding a thin metal plate, and upper and lower slits are formed along the longitudinal direction of the female terminal at the cylindrical elastic portion. Further, at the end of the cylindrical elastic portion, two pairs of flat plate-shaped contact portions (four in total) are formed along the circumference of the free end of the female terminal, as electric contact portion with the male connector inserted into the cylindrical elastic portion of the female terminal. In this female terminal, additionally a contact projection is formed at each inner surface of the flat plate-shaped contact portions to increase the contact reliability between the male and female terminals. In the above-mentioned female terminal, since two pairs of the flat plate-shaped contact portions each pair formed via a circular arc-shaped bent portion are formed on both sides of the slits, respectively; in other words, since the electric contact portions of the female terminal are formed being bent into flat shape, it is possible to improve the manufacturing precision of the space dimension between the two opposing flat plate-shaped contract portions, because the female terminal can be bent by use of an appropriate press machine.
When the male terminal pin is inserted into a roughly square hollow portion enclosed by the flat plate-shaped contact portions of the female terminal, since the contact projections formed in the flat plate-shaped contract portions of the female terminal, respectively can be firmly brought into contact with the outer circumferential surface of the pin portion of the male terminal, a stable electrical contact can be attained.
In the conventional female terminal, however, when one of the contact projections formed in the flat plate-shaped contact portions of the female terminal drops into a V-shaped groove formed at the junction portion between the two ends of the rounded thin metal plate of the male terminal, since the male and female terminals are connected to each other in eccentric state, there exists a problem in that the electric contact reliability deteriorates.